1. Field of the Invention
The present invention relates to an image pickup unit that is used mainly in an endoscope apparatus of a side-view type, an oblique-view type, or the like and includes a prism that converts an optical path of photographing light.
2. Description of the Related Art
In recent years, endoscopes have been widely used in medical fields and industrial fields. As for an endoscope in the past, a mainstream is an endoscope in which an image guide is used and with which a user can observe an inside of a body cavity of a patient, an inside of a jet engine, or the like in an eyepiece section that the user looks into.
Further, as an endoscope in these days, an electronic endoscope apparatus emerges that incorporates an image pickup unit, photographs an inside of a body cavity of a patient, an inside of a jet engine, or the like, and displays an endoscope image on a display device such as an external monitor. As such an electronic endoscope, according to uses, there are a front-view type endoscope, an observation direction of which is a direction along a long axis of an insertion section, and a side-view type (oblique-view type) endoscope apparatus, an observation direction of which is a direction having a predetermined angle with respect to the long axis of the insertion section.
In the side-view type (oblique-view type) endoscope apparatus, an image pickup unit that picks up an image in the observation direction having the predetermined angle with respect to the long axis of the insertion section is incorporated. In the image pickup unit, a prism, which is an optical path converting optical component, for reflecting observation light and converting the observation direction disclosed in, for example, Japanese Patent Application Laid-Open Publication Nos. 2005-121967, 2006-201796, and 09-262207 is provided.